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	<head>
		<title>three.js ar - camera access</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
		<link type="text/css" rel="stylesheet" href="main.css">
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		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> ar - camera access<br/>
		</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';
			import { ARButton } from 'three/addons/webxr/ARButton.js';

			const clock = new THREE.Clock();

			let camera, scene, renderer;
			let cube;

			init();

			async function init() {

				const container = document.createElement( 'div' );
				document.body.appendChild( container );

				scene = new THREE.Scene();

				camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.01, 20 );

				const defaultLight = new THREE.HemisphereLight( 0xffffff, 0xbbbbff, 3 );
				defaultLight.position.set( 0.5, 1, 0.25 );
				scene.add( defaultLight );

				//

				renderer = new THREE.WebGLRenderer( { antialias: true, alpha: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				renderer.xr.enabled = true;
				container.appendChild( renderer.domElement );

				//

				document.body.appendChild( ARButton.createButton( renderer, { requiredFeatures: [ 'camera-access' ] } ) );

				//

				const boxGeometry = new THREE.BoxGeometry( 1, 1, 1 );
				const boxMaterial = new THREE.MeshStandardMaterial();
				cube = new THREE.Mesh( boxGeometry, boxMaterial );
				cube.position.z = - 3;

				scene.add( cube );

				//

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			//

			function setCameraTexture() {

				if ( ! renderer.xr.getSession() ) {

					if ( cube.material.map ) {

						cube.material.map = null;
						cube.material.needsUpdate = true;

					}

					return;

				}

				const frame = renderer.xr.getFrame();
				const referenceSpace = renderer.xr.getReferenceSpace();

				if ( ! frame || ! referenceSpace ) return;

				const viewerPose = frame.getViewerPose( referenceSpace );

				if ( ! viewerPose ) return;

				const view = viewerPose.views.find( view => view.camera );
			
				const cameraTexture = renderer.xr.getCameraTexture( view.camera );

				if ( cube.material.map === cameraTexture ) return;

				cube.material.map = cameraTexture;
				cube.material.needsUpdate = true;
			
			}

			function animate() {

				const delta = clock.getDelta();

				setCameraTexture();

				cube.rotation.x += delta;
				cube.rotation.y += delta;

				renderer.render( scene, camera );

			}

		</script>
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